1. Field of the Invention:
The present invention relates to a canned submersible motor for a deep well pump, and is particularly concerned with a pump mounting structure of the canned motor.
2. Prior Art
A canned submersible motor for a deep well pump is well known and a typical example of such a motor mounted on a pump is shown in FIG. 2.
As is shown generally in FIG. 2, a prior art deep well pump has a suction port 103 provided at a mounting part positioned between an upper pump element 101 and a lower motor element 102, and thus when the pump operates, water in a deep well is sucked in from the suction port 103 as indicated by arrows, pressurized by the multistage pump element 101, and fed externally from an upper discharge port 104 through a discharge pipe not shown.
FIG. 3 is a longitudinal sectional view of a prior art canned submersible motor for a deep well pump corresponding to the aforementioned motor element 102. In the illustration, the motor comprises a stator chamber constructed integrally by welding a stator core 111, a frame or outside can 112, an inside can 113, a load side (or pump mounting side) end plate 114 and a counter load side end plate 115 to each other, bearing brackets 116 and 117 mounted on a load side and a counter load side of the stator chamber respectively for supporting a shaft 119 and a radial bearing 124, 125, a rotor 118 and the shaft 119 constructing a rotator, a downward thrust bearing 120 for supporting the rotator axially, and a thrust bearing case 121 for containing the thrust bearing 120.
A motor mounting flange 122a of a pump suction casing 122 indicated by a two-dot chain line is mounted on a pump mounting flange 116a of the bearing bracket 116 of the motor, and thus at the time of pump operation, water is sucked in from a pump suction port 122b of the pump suction casing 122 toward an inlet port of a pump body (not shown) as indicated by arrows. In the illustration, a reference numeral 111a denotes a stator coil winding and 123 denotes a power cable.
In the above-described prior art canned motor for deep well pump, however, since the suction port 122b is provided on the pump suction casing 122 which is in turn mounted on the bearing bracket 116, at the time of operation, pumped-out water flows at a position far away from the heat source, i.e. a stator coil winding 111a, by way of the load side end plate 114, the bearing bracket 116 and the motor mounting flange 122a of the pump inlet casing 122, therefore almost no cooling effect is exerted on the winding 111a.
Further, since the suction casing 122 and the bearing bracket 116 are axially connected, an axial length of a total unit will inevitably become too long.